100 LIGHT SCIENCE FOR LEISURE HOURS. 



passing, as a remarkable and unforeseen circumstance, 

 that the farther north the voyagers went the less severe 

 was the cold they had to encounter. We shall see that 

 this circumstance has an important bearing on the con- 

 siderations we shall presently have to deal with. 



One other circumstance respecting the search for the 

 north-west passage, though not connected very closely 

 with our subject, is so singular and so little known that 

 we feel tempted to make mention of it at this point. 

 The notion with which the seekers after ,a north-west 

 passage set out was simply this, that the easiest way of 

 reaching China and the East Indies was to pursue a 

 course resembling as nearly as possible that on which 

 Columbus had set out if only it should appear that 

 no impassable barriers rendered such a course imprac- 

 ticable. They quickly found that the American conti- 

 nents present an unbroken line of land from high 

 northern latitudes far away towards the antarctic seas. 

 But it is a circumstance worth noticing, that if the 

 American continents had no existence, the direct 

 westerly course pursued by Columbus was not only not 

 the nearest way to the East Indian Archipelago, but 

 was one of the longest routes which could possibly have 

 been selected. Surprising as it may seem at first sight, 

 a voyager from Spain for China and the East Indies 

 ought, if he sought the absolutely shortest path, to set 

 out on an almost direct northerly route ! He would 

 pass close by Ireland and Iceland, and so, near the 

 North Pole, and onwards into the Pacific. This is 

 what is called the great-circle route ; and if it were only 



